X-ray Flares of EV Lac: Statistics, Spectra, Diagnostics

Abstract

We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape, and scale. The flares range from very short (<1 ks) to long (10 ks) duration events with a range of shapes and amplitudes for all durations. We extract spectra for composite flares to study their mean evolution and to compare flares of different lengths. Evolution of spectral features in the density-temperature plane shows probable sustained heating. The short flares are significantly hotter than the longer flares. We determined an upper limit to the Fe K fluorescent flux, the best fit value being close to what is expected for compact loops.

9 pages; 9 figures; latex/emulateapj style; Submitted to The Astrophysical Journal

References in corpus (8)

• Large-scale magnetic topologies of early M dwarfs
• Highly Efficient Modeling of Dynamic Coronal Loops
• Diagnostics of stellar flares from X-ray observations: from the decay to the rise phase
• The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind
• Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a Superflare on II Pegasi
• X-ray Fluorescent Fe Kalpha Lines from Stellar Photospheres
• On X-ray Optical Depth in the Coronae of Active Stars
• Magnetic fields in M dwarfs: rapid magnetic field variability in EV Lac

Cited by in corpus (11)

• Suppression of Coronal Mass Ejections in active stars by an overlying large-scale magnetic field: A numerical study
• The Stellar CME-flare relation: What do historic observations reveal?
• Understanding extreme quasar optical variability with CRTS: I. Major AGN flares
• Detection of Flare-induced Plasma Flows in the Corona of EV Lac with X-ray Spectroscopy
• Simultaneous Multiwavelength Flare Observations of EV Lacertae
• Detection of Flare-associated CME Candidates on Two M-dwarfs by GWAC and Fast, Time-resolved Spectroscopic Follow-ups
• Stellar flares and the dark energy of CMEs
• A 33 year constancy of the X-ray coronae of AR Lac and eclipse diagnosis of scale height
• Flaring-associated Complex Dynamics in Two M-dwarfs Revealed by Fast, Time-resolved Spectroscopy
• First Millimeter Flares Detected from Epsilon Eridani with ALMA
• (Simulating) Coronal Mass Ejections in Active Stars